Heart Sounds

1

• Heart Sounds
• Heard with the aid of a stethoscope
• First sound Lub
• - caused by closure of AV valves
• Second sound Dup
• - caused by closure of aortic and
  pulmonary valves

2

• Blood Pressure
• The force exerted by the blood
• on the blood vessel wall
• Expressed in millimetres of mercury (mmHg)
• Systolic 120mmHg
• Diastolic 80mmHg

BP

3

• Systolic
• - Contraction of ventricles
• - Emptying phase
• Diastolic
• - Relaxation of ventricles
• - Filling phase

4

• Blood always enters the heart via the atria
• Blood always leaves the heart via the ventricles
• Cardiac Output
• Volume of blood ejected (pumped) by the
  ventricles per minute.
• Stroke Volume
• Volume of blood ejected by each ventricle
  per contraction

5

• Cardiac Output Heart Rate x Stroke Volume
• CO HR x SV
• E.g.
• At Rest
• 5 litres / min 70 ml x 75 beats / min
• Heavy Exercise
• 25 litres / min 140 ml x 200 beats / min

6
Distribution of CO
Weight
Blood Flow
CO
7

• Mean Arterial Cardiac x Peripheral
• Blood Pressure Output Resistance
• MABP CO x TPR
• CO HR x SV
• Resistance dependent on
• - blood viscosity
• - blood vessel length
• - blood vessel diameter